Hydrophobic non-adherent wound dressing

ABSTRACT

A resilient, substantially flat, non-adherent flexible wound dressing which remains flexible when dry, of hydrophobic material capable of retaining substantial quantities of fluid wound exudate. One or both major surfaces may be non-adherent woundcontacting surfaces which may include fenestrated film or interrupted exposed portions of flattened sheetlike fused fibers having a filmlike appearance, or both. The interior of hydrophobic fibers is arranged to retain fluid wound exudate by capillary action. If superimposed fenestrated film is used, it may be united to the hydrophobic fibers either at or inside the dressing edges, or both, preferably by melt sealing. Dressings may be prepared by pressing (with substantially no relative movement) the hydrophobic fibrous material, preferably a carded or air laid batt together with any fenestrated film between closely adjacent parallel uni-directionally moving surfaces of a foam and a stainless steel belt which is heated and then cooled. In the absence of a covering fenestrated film, the surface fibers of the batt, pressed against the heated belt, are softened, flattened, fused and subsequently congealed in contact with the polished belt, thereby forming sheetlike interrupted surface areas of filmlike appearance. When a fenestrated film is added to the dressing, it passes in contact with the stainless belt and may be melt sealed in passage to the fibrous batt with sheetlike interrupted areas of fused fibers being formed, or not formed depending upon the temperature the fibers reach, through the holes in the fenestrated film. A melt edge version of the dressing with soft edges may be made with a cooled perimeter clamp adjacent which a hot perimeter knife cuts and seals the dressing edge.

United States Patent Mack et al.

[451 Nov. 28, 1972 [54] HYDROPHOBIC NON-ADHERENT WOUND DRESSING [72]Inventors: Robert J. Mack; John L. Fischer,

both of Arlington Heights, Ill.

[73] Assignee: The kendall Company, Walpole,

Mass.

[22] Filed: Oct. 9, 1969 [21] Appl. No.: 864,989

[52] US. Cl ..128/156 [51] Int. Cl. ..'.....A61l 15/01 [58] Field ofSearch .128/156, 296; 15/244 R, 244 B; 131/267, 268, 269

[56] References Cited UNITED STATES PATENTS 3,545,442 12/1970 Wicker etal. ..128/156 3,528,417 9/1970 Gardner ..128/156 3,313,665 4/1967 Berger..131/267 3,189,506 6/1965 Cobb, Jr. et al. ..131/269 X PrimaryExaminer-Robert W. Michell AttorneyRobert D. Chodera 57 ABSTRACTsurfaces may be non-adherent wound-contacting surfaces which may includefenestrated film or interrupted exposed portions of flattened sheetlikefused fibers having a filmlike appearance, or both. The interior ofhydrophobic fibers is arranged to retain fluid wound exudate bycapillary action. If superimposed fenestrated film is used, it may beunited to the hydrophobic fibers either at or inside the dressing edges,or both, preferably by melt sealing.

Dressings may be prepared by pressing (with substantially no relativemovement) the hydrophobic fibrous material, preferably a carded or airlaid batt together with any fenestrated film between closely adjacentparallel uni-directionally moving surfaces of a foam and a stainlesssteel belt which is heated and then cooled. In the absence of a coveringfenestrated film, the surface fibers of the batt, pressed against theheated belt, are softened, flattened, fused and subsequently congealedin contact with the polished belt, thereby forming sheetlike interruptedsurface areas of filmlike appearance. When a fenestrated film is addedto the dressing, it passes in contact with the stainless belt and may bemelt sealed in passage to the fibrous batt with sheetlike interruptedareas of fused fibers being formed, or not formed depending upon thetemperature the fibers reach, through the holes in the fenestrated film.

A melt edge version of the dressing with soft edges may be made with acooled perimeter clamp adjacent which a hot perimeter knife cuts andseals the dressing edge.

13 Claim, 8 Drawing Figures PATiNTEmwvza m2 3,703,897

f 0 0 JO HY DROPHOBIC NON-ADHERENT WOUND DRESSING This invention relatesto that class of wound dressings including a contact surface which isnon-adherent to wounds and wound exudates, the dressing providing forremoval from the wound site of liquid wound exudates, thus causing theformation of a very thin flexible eschar.

BACKGROUND OF THE INVENTION An early dressing of the subject typedisclosed in US. Pat. No. 2,923,298 to W. B. Dockstader et al.,comprised a fenestrated smooth wound-contacting film united at pointsbetween the openings to an absorbent unified backing including nonwovensheets and cotton gauze. A thinner version of the Dockstader dressing,using a single layer of cotton gauze, is disclosed in the Fukuda U. S.Pat. No. 3,446,208. Numerous other variations of the Dockstaderdressing, largely concemed with the wound-contact surface, have beenproposed, among which are the dressings described in the Eldredge et al.U. S. Pat. No. 3,285,245, and those described in the Davies U. S. Pat.No. 3,006,338. In the Eldredge variation the contact film is aparticular discontinuous film of fused and coalesced nonwoven finedenier polypropylene fibers. The Davies patent impregnates a nonwovenfabric of about the weight of cleaning tissue with a polyethyleneemulsion which after drying is calendered to produce a contact surface.Both of these variations and others unite the woundcontacting film orlayer with an absorbent material, preferably in the form of cotton,rayon, cellulosic batts, etc., to produce a complete dressing, however.Such absorbent materials form excellent dressing components when thedressing is changed frequently before the exudate saturated absorbentportions of the dressings become dried. Exudate saturated absorbentmaterials do have the detrimental feature when dried, however, ofbecoming stiff, harsh and inflexible. If, after drying, they remain incontact with the wound which is already in traumatic condition, they areextremely uncomfortable and frequently aggravate the trauma. While thereason for stiff drying is not entirely clear, a possible explanationmay be that the exudate and the absorbent material have an affinity forwater which is known to swell absorbent fibers. Hence there is anintimate association possibly with some exudate being imbibed with itswater into the fiber, forming when dried a continuous matrix reinforcedby the exudate stiffened absorbent material. Additionally, whateverwater is absorbed in the absorbent fiber comes from the exudate andhence the absorbent material more quickly reduces the dressing to thestiff dried condition than would be the case if no absorbent materialwere present.

SUMMARY OF THE INVENTION It is a primary object of this invention toprovide a suitably non-adherent dressing which not only will retainadequate amounts of wound exudate, thereby avoiding frequent dressingchanging, but one which remains soft and flexible even when the retainedexudate has dried. The primary object of the invention is attained byeliminating absorbent material from the dressing. The intimateassociation of absorbent materia1 and wound exudate, which is the mostsignificant factor in stiff drying of wound dressings, is therebyavoided. The dressing of this invention is, therefore, whollyhydrophobic, not only with regard to the wound-contact surface whichbecause of its porous nature permits the exudate to contact thesubsurface capillaries of the dressing, but also with regard to thefibrous layers which are themselves hydrophobic and whose capillaryinterstices draw the exudate away from the wound into the dressinginterior. Wound dressings of this invention are filled from the woundside with exudate by capillary action, the interconnecting interstice'scausing the dressings to fill until the capillary space is occupied,thus avoiding contact between the drying atmosphere and the woundexudate except at the peripheral surface areas. But even when theexudate is completely dry, the dressing does not have thecharacteristics of a solid matrix but rather remains flexible. Apossible explanation may be that the exudate which fills only capillaryinterstices dries into an extremely fragile three dimensional network ofindividual dried strands which remain flexible because of theirthinness.

The hydrophobic dressings of this invention are of two species, one ofwhich is wholly fibrous initially but one or more surfaces of which aresoftened, flattened and formed by contact against a hot polished surfaceand cooled thereon, forming a soft comfortable nonadherent wound-contactsurface including interrupted sheetlike areas of fused hydrophobicfibers having a filmlike appearance. The interrupted filmlike areas arebridged by underlying subsurface fibers of the fibrous capillaryinterior of the dressing. The contact surface wicks the wound exudateinto the dressing interior where it dries, leaving the dressing stillflexible. Only a thin layer of exudate is left in contact with thewound. This thin layer dries to a flexible eschar film adherent to thewound.

The other species of dressing of the invention, which is the preferredone, may simply be the first species with a fenestrated thin filmbetween what would be the contact surface otherwise and the wound. Thefilm may be united to the underlying fibrous material either in themanner illustrated in the Dockstader patent, around the holes, at pointsbetween the holes, or only at the peripheral edges. The underlyingfibrous pad which forms the interior of the dressing, being somewhatresilient, tends to press its surface fibers against and even somewhatinto the fenestrated film holes to make its capillarity available to thewound exudate. However, it is unnecessary when a fenestrated film isinterposed that the underlying fibrous surface have interruptedsheetlike areas of fused hydrophobic fibers having a filmlike surface.Moreover, when fenestrated film is used on both major surfaces and thefilms are sealed together around the dressing edges, it is evenunnecessary to have an integrated fibrous interior although it ispreferred that the fibrous layer be integrated. Obviously, if the filmis on one surface only, at least the exposed fibrous back should beintegrated to prevent fiber shedding. But when fenestrated filmfaceddressings are prepared by passing them through the apparatus of FIG. 7,they may be passed through at a faster rate or at reduced temperatureswhereby fusion between the film and the underlying structure is achievedwithout appreciably flattening the surface fibers bridging the filmholes. However, if there are protruding fiber ends, these are softened,bent back and usually fused to the edges of the holes or to otherfibers. All of these variations are suitable, although some give betterresults than others.

While it is preferred that the layers of hydrophobic fibers used in thepreparation of the dressings of this invention be assembled by airlaying or carding, the method of assembly is not critical nor is thespacial relationship of the fibers or, if integrated, their method ofunification, either by the use of binders, solvents, heat, mechanicalintermeshing or by other means. What is critical is that the layers musthave capillarity. Fibrous layers of hydrophobic material can normally bemade to exhibit capillarity since if the interfiber spacing is too greatto support capillary action, the layers may be compressed until theinter-fiber spacing will support capillary action.

Preferred hydrophobic fibers for the hydrophobic fibrous layers used inthe preparation of the dressings of this invention are those preparedfrom polyolefins, polyesters, acrylics, polyvinyls, polyamides andvarious mixtures thereof, although all of the known flexible hydrophobicpolymeric fibers are suitable. Fibers as coarse as 50 denier and above,while not preferred because of their stiffness and comparatively highresiliency in some cases, are suitable so long as the layers assembledfrom them have capillarity. The stiffness of such higher denier fibersmay be somewhat alleviated by non-toxic plasticizers, as is well known.

But finer fibers in the denier range, from the finest commerciallyavailable to 8 denier, are preferred because dressings made inaccordance with the invention from such fibers display softness,conformability and adequate resiliency to provide cushioning protectionto wounds from normally encountered forceful contacts.

It is characteristic of hydrophobic fibrous capillary layers that whencompressed there is a distinct tendency for sheetwise capillary flow ascompared with penetrating flow. Penetrating flow is more pronounced inless compressed areas or layers of the same fibers prepared under thesame conditions. A possible explanation might be that, in compressingthe layers, the fibers and hence the capillary channels are bent ordeflected in sheetwise direction to a greater degree. At any rate, thephenomenon exists and advantage is taken of it in the preferreddressings of the invention by incorporating at least one densified orcompressed layer. In one such dressing, the outer layers of the fibrousthickness are separated by a more compressed or densified layer, whichwhile being penetrated spreads the fluid over a greater sheetwise areaof the dressing. The spread fluid then moves from this enlarged areainto both outer layers by capillary action, thus avoiding saturation ina local area.

In this invention, the size of the holes in any fenestrated film,preferably in the range of 0.025 inch to 0.035 inch in diameter and theopen area, (hole area)/(total area), preferably 10 to 25 percent, andnot critical so long as the open area is sufficient and the holes arelarge enough to permit passage of the exudate. This latter variessomewhat in that exudate which is more viscous requires a larger holethan blood or burn fluids. Larger holes which might otherwise beobjectionable because of the fibrous nature of the underlying capillarylayer may be used when the holes are at least partially bridged by theinterrupted skinlike smooth porous film areas of softened flattened andfused surface fibers of the underlying fibrous layer.

The thickness of the interposed fenestrated film, where such film isused, again is not critical. However, in addition to the fact that thinfilms are generally softer and more conformable than thick films, theyare preferred because of the fact that the thickness and flexibility ofthe eschar remaining covering the wound is related to the filmthickness. For that reason, films in the range of 0.00025 inch to 0.001inch are preferred although flexible films of considerably greaterthickness can be used less effectively.

The properties of the dressings of this invention can perhaps best beillustrated by comparison with the most widely used non-adherentdressing marketed today, dressing A made in accordance with theDockstader et al. patent teaching and sold under the trademark TELFA byThe Kendall Company, 225 Franklin Street, Boston, Mass. This dressingcomprises an outer envelope of V4 mil fenestrated polyethyleneterephthalate film and an absorbent nonwoven feltlike layer of cottonunited to the film at points between the holes therein. Dressing B ofthis invention, with which the TELFA non-adherent dressing was compared,con sisted of an outer envelope of /4 mil fenestrated polypropylene filmand a filling layer of partially fused polypropylene fibers averaging 3denier with a fiber length of about 1 1% inches. This dressing waspassed twice through the apparatus of FIG. 7 and the film and fibrouslayer were fused together around the holes at least but in only a few ofthe holes were any of the interrupted skinlike film areas shown in FIG.6 exhibited. The dressing was edge sealed on the apparatus of FIG.

In testing the fluid take-up rate of the dressings, an apparatus wasused which delivers the fluid to a well and maintains the well level atdressing-contact level. The dressing was placed wound-contact surfacedown over the liquid-filled well and the time necessary for the dressingto take up 5 ml. of fluid was recorded.

The fluid retention test was the so-called dunk and drain 'test in whichthe dressings were immersed in water until thoroughly saturated and thenafter draining for 10 minutes were weighed to determine the gain overthe dry weight under ambient conditions. The test utilized was ASTM No.D1117.

Figures given in Table I below are average figures.

TABLE I Dessing A Dressing B Size 3 8inches 3 8inches Weight 2.45 grarm2.60 grarm Fluidup-takerate 5mlin20sec. 5mlinl5sec. "Dunk & Fluidretention 25.25 pan 27.16 grams The comparative stiffness of thedressings were measured before wetting and after being wetted with 10ml. of blood, and dried. Stifi'ness was measured using a modifiedcantilever method whereby similar size dressings were similarly clampedto a rotatable cantilever arm with the dressing initially horizontal andjust contacting but not depressing a knife edge on a balance arm. As thecantilever arm was rotated through 90 toward the balance, the amount ofdownward force exerted by the bending dressing against the balance knifeedge was recorded for each of rotation. When the dressings were comparedbefore wetting, the force exerted by the dressings was very similar,varying from about 0.6 gram to 2.3 grams in bending from 10 through 90.After being wetted with the same amount of blood and dried, however, theforce exerted by the two dressings was as follows:

TABLE II Dressing A Dressing B 10 6.0 grams 2.5 grams 20 10.3 grams 4.0grams 30 13.9 grams 5.3 grams 40 15.7 grams 6.0 grans 50 17.3 grams 6.1grams 60 17.7 grams 5.5 grams 70 18.4 grains 5.3 grams 80 18.0 grams 5.3grams 90 18.1 grams 5.3 grams BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1illustrates a preferred wound dressing of the invention 10 with a turnedup corner including a fenestrated contact film 11 with openings 13 whichare bridged by hydrophobic fibrous surface areas 16 of a hydrophobicfibrous layer (FIG. 2). The preferred dressing has a melt sealedcontinuous edge 14 and a carded hydro-phobic fiber back surface 12.

FIG. 2 is a cross section of the dressing along the line 2 2' of FIG. 1looking in the direction of the arrows, showing the internal hydrophobicfibrous layer 15 which must demonstrate capillarity.

FIG. 3 is a variation of the invention with films similar to 11 on bothsides of the dressing of FIG. 1, the illustrated cross section showingfenestrated films 21 and 21, the openings in which are bridged byhydrophobic fibrous surface areas similar to 16 in FIG. 1, thecontinuous edge 24 and the internal fibrous structure 25 also beingsimilar to respective edge 14 and fibrous structure 15 of FIGS. 1 and 2.While in the embodiment of FIG. 3 the internal fibrous structure 25 andthe film 21 and 21 are sealed together at the edge 24, in anon-preferred but workable embodiment the fibrous structure is merelycontained in the film envelope without being sealed or otherwisefastened thereto.

FIG. 4 is another variation of the wound dressing of FIG. 1 wherein thedressing has major surfaces 36 and 36' which have no superimposedfenestrated film 1 1. These surfaces include interrupted skinlike smoothporous film areas of fused and melted surface fibers of a hydrophobicfibrous layer (preferably of fibers similar to those of the interiorwith underlying and bridging hydrophobic fibers. The internal structureof hydrophobic fibers 35 and the sealed edge 34 are similar to theircounterparts in FIGS. 1 and 2.

FIG. 5 shows a cross section of a dressing of the invention in one ofits most simple forms. The dressing 50 consists of integrated layers ofhydrophobic fibers 75, 75' and 78 of demonstrated capillarity and awoundcontact major surface 76 of interrupted skinlike smooth porousareas of fused and melted surface fibers of fibrous layer 75. The backmajor surface 79 of the dressing 50 is not different from the fluidretaining body 75'. The layer 78 is a layer of more compactedhydrophobic fibers which tends to spread the fluid as it passes through.

Obviously, dressings may be constructed within the inventionincorporating one or more of the illustrated non-critical variations andothers, so long as the dressings respond to the claims.

FIG. 6 illustrates a typical microphotographic appearance ofwound-contact surfaces 36, 36 and 76 of the dressings of FIGS. 4 and 5at 150 magnification showing the interrupted skinlike smooth porous filmareas 71 of softened and fused hydrophobic fibers with openings 73(between the smooth film areas 71) bridged by underlying fibers 72.

FIG. 7 illustrates schematically apparatus useful in producing from afibrous batt the wound-contact surfaces similar to FIG. 6 on thedressings of the invention similar to those illustrated in FIGS. 4 and5. The apparatus comprises two endless contacting belts, one (51) ofpolymeric foam and the other (52) of stainless steel, which press thepreferably continuous fibrous dressing and optionally fenestrated filmbetween them, wound-contact surface against the stainless steel belt.Whenever both major surfaces of the dressing are to be wound-contactsurfaces, the dressing must be inverted and run through the machineagain, or two such machines could be used. Alternatively, a springloaded stainless steel belt could replace the foam belt. The belts arestretched taut between drums 53 and 54 (which turn with their respectiveshafts 55 and 56 in fixed bearings) and respective drums 57 and 58 whoseshafts 59 and 60 are in adjustable bearings being movable with respectto the frame 67 on crossheads 61 and 62 by respective adjustment screws63 and 64. Similar adjustable features are at the opposite side of therespective belts. The stainless steel belt 52 is heated by means of gasburners 65 whose flame contacts the under side of the belt. The burnersare insulated from cold water jets 66 which rapidly cool the previouslyheated stainless steel belt with which the softened and flattenedsurface fibers of the hydrophobic dressing on the fenestrated film arestill in contact. Passage through the apparatus at proper temperaturesforms skinlike smooth film areas of the surface fibers which contact thehot belt. The interrupted fibrous surface retains capillarity becausethe softened fibers are allowed to flow only to a limited extent and arechilled before the interstices can be closed. Capillaries also exist inthe areas bridging the fused surface fibers.

In FIG. 8 a device 40 is illustrated schematically for forming thinflexible melt fused edges such as the edge 14 of FIGS. 1 and 2 on thedressings of the invention. The device consists of a chilled peripheralhold-down clamp 44 which has means for raising and lowering it intoclamping relationship. A contour die 42 heated by means of heater coil41 melts through and seals the thermoplastic dressing material as itdescends, compressing spring 43, the elements of which obviously musthave sufficient spacing to permit such action. The peripheral heatededge 45 moves closely adjacent the cooled peripheral clamp edge 46. Thedie is withdrawn by the action of spring 43 when the downward pressureis released. While it is preferred that when a fenestrated film is to beused on the dressings of the invention it be fastened to the underlyingfibrous batt by the apparatus of FIG. 7, the film may be fastened byother means including those described in the above mentioned Dockstaderet al. patent, or alternatively the fenestrated film such as 11 in FIG.1 may be completely unsecured to the underlying batt except at the edgeswhich may be sealed by the heated edge 45 or otherwise. In the envelopeembodiment of FIG. 3, it is not essential that the fibrous structure andthe film be fastened together.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred embodiment ofthis invention is a dressing similar to that illustrated in FIG. 1except that the fibrous portion which retains the wound exudate is inthree layers which are carded and compressed, with the central layercompressed more than the two outer layers. All layers are preferablymade of 3 denier polypropylene fibers about 1 inches in length with thetotal weight of the fibrous portion being in the range of 100 to 200grams per square yard. The film is V4 mil polypropylene fenestrated with0.025 to 0.035 inch diameter holes to give an open area of about to 25percent. The dressing fabric is run through the apparatus (FIG. 7) atsuch speed that the film is heated to about 300 F. and then is rapidlycooled in contact with the stainless steel belt as it moves through theapparatus. The individual dressings are then edge sealed on theapparatus of FIG. 8.

The next preferred dressing is made with the same fibrous layers fromthe same materials with the film omitted. The material is again runthrough the apparatus of FIG. 7 under the same conditions as with filmbut the fibrous surface which is in contact with the stainless steelroll has its contacting fibers softened, flattened and fused to form awound-contact surface similar to that illustrated in FIG. 6 (magnified).Both of the preferred dressings retain adequate amounts of woundexudate, are satisfactory as to non-adherence to wounds and woundexudates, and remain flexible when retained blood is dried.

We claim:

1. In a unitary non-adherent flexible wound dressing capable of removingfrom the wound site appreciable quantities of fluid wound exudate and.retaining it separated therefrom, that improvement wherein the surfaceson both sides of the dressing are hydrophobic and the dressing includesa flexible noncellular nonwoven layer of discrete fibers, all of whichare hydrophobic, providing fluid retentive inter-fiber capillarity withthe major portion of said discrete fibers of said layer being located inthe interior of said layer to provide bulk 8 to the dressing and atleast one of said surfaces being a porous non-adherent wound-contactsurface.

2. The dressing of claim 1 wherein the contact surface includes areas ofinterrupted sheetlike fused hydrophobic fibers having a filmlikeappearance.

3. The dressing of claim 2 wherein the interrupted areas of sheetlikefused hydrophobic fibers and a wound-contact surface are coextensive.

4. The dressing of claim 2 wherein the interrupted areas of sheetlikefused hydrophobic fibers are coextensive with both ma'or surfacesthereof.

5. The dressmg 0 claim 1 wherein the wound-contact surface includes atleast one fenestrated hydrophobic film, the openings in which arebridged by surface fibers of the flexible hydrophobic fibrous layer.

6. The dressing of claim 5 wherein the openings are at least partiallybridged by interrupted areas of sheetlike fused hydrophobic fibershaving a filmlike appearance.

7. The dressing of claim 5 wherein the layer of fibers is integrated atleast on the exposed surfaces thereof.

8. The dressing of claim 5 wherein surface fibers of the hydrophobicfibrous layer are sealed to the fenestrated hydrophobic film.

9. The dressing of claim 5 having two major woundcontact surfacesincluding fenestrated hydrophobic film united at the dressing edges.

10. The dressing of claim 1 wherein the hydrophobic fibers arepolyolefin fibers.

11. In a unitary non-adherent flexible wound dressing capable ofremoving from the wound site appreciable quantities of fluid woundexudate and retaining it separated therefrom, that improvement whereinthe dressing is hydrophobic and comprises at least two flexiblenoncellular nonwoven layers of discrete hydrophobic fibers, providingfluid retentive inter-fiber capillarity, one of which layers is moredense than another layer, and wherein the major portion of said discretefibers of said layers is located in the interior of said layers andprovides bulk to the dressing and at least one major porous hydrophobicnon-adherent wound-contact surface.

12. The dressing of claim 1 1 wherein the contact surface includesinterrupted areas of sheet-like fused hydrophobic fibers at the surfaceof the outermost layer of the dressing, said surface having a film-likeappearance.

13. The dressing of claim 11 wherein the wound-contact surface includesat least one fenestrated hydrophobic film, the openings in which arebridged by surface fibers of the outermost surface of said hydrophobicfibrous layers.

2. The dressing of claim 1 wherein the contact surface includes areas ofinterrupted sheetlike fused hydrophobic fibers having a filmlikeappearance.
 3. The dressing of claim 2 wherein the interrupted areas ofsheetlike fused hydrophobic fibers and a wound-contact surface arecoextensive.
 4. The dressing of claim 2 wherein the interrupted areas ofsheetlike fused hydrophobic fibers are coextensive with both majorsurfaces thereof.
 5. The dressing of claim 1 wherein the wound-contactsurface includes at least one fenestrated hydrophobic film, the openingsin which are bridged by surface fibers of the flexible hydrophobicfibrous layer.
 6. The dressing of claim 5 wherein the openings are atleast partially bridged by interrupted areas of sheetlike fusedhydrophobic fibers having a filmlike appearance.
 7. The dressing ofclaim 5 wherein the layer of fibers is integrated at least on theexposed surfaces thereof.
 8. The dressing of claim 5 wherein surfacefibers of the hydrophobic fibrous layer are sealed to the fenestratedhydrophobic film.
 9. The dressing of claim 5 having two majorwound-contact surfaces including fenestrated hydrophobic film united atthe dressing edges.
 10. The dressing of claim 1 wherein the hydrophobicfibers are polyolefin fibers.
 11. In a unitary non-adherent flexiblewound dressing capable of removing from the wound site appreciablequantities of fluid wound exudate and retaining it separated therefrom,that improvement wherein the dressing is hydrophobic and comprises atleast two flexible noncellular nonwoven layers of discrete hydrophobicfibers, providing fluid retentive inter-fiber capillarity, one of whichlayers is more dense than another layer, and wherein the major portionof said discrete fibers of said layers is located in the interior ofsaid layers and provides bulk to the dressing and at least one majorporous hydrophobic non-adherent wound-contact surface.
 12. The dressingof claim 11 wherein the contact surface includes interrupted areas ofsheet-like fused hydrophobic fibers at the surface of the outermostlayer of the dressing, said surface having a film-like appearance. 13.The dressing of claim 11 wherein the wound-contact surface includes atleast one fenestrated hydrophobic film, the openings in which arebridged by surface fibers of the outermost surface of said hydrophobicfibrous layers.